1. Field of Invention
The present invention generally relates to the field of medical devices. Some embodiments of the invention relate to spinal implants inserted in patients during surgical procedures and to instruments used to insert the implants. Some embodiments of the invention relate to instruments for preparing a space for an implant. Other embodiments of the invention relate to methods for positioning an implant during a surgical procedure.
2. Description of Related Art
An intervertebral disc may degenerate. Degeneration may be caused by trauma, disease, and/or aging. An intervertebral disc that becomes degenerated may have to be partially or fully removed from a spinal column. Partial or full removal of an intervertebral disc may destabilize the spinal column. Destabilization of a spinal column may result in alteration of a natural separation distance between adjacent vertebrae. Maintaining the natural separation between vertebrae may prevent pressure from being applied to nerves that pass between vertebral bodies. Excessive pressure applied to the nerves may cause pain and/or nerve damage. During a spinal fixation procedure, a spinal implant may be inserted in a space created by the removal or partial removal of an intervertebral disc between adjacent vertebrae. The spinal implant may maintain the height of the spine and restore stability to the spine. Bone growth may fuse the implant to adjacent vertebrae.
A spinal implant may be inserted during a spinal fixation procedure using an anterior, lateral, posterior, or transverse spinal approach. A discectomy may be performed to remove or partially remove a defective or damaged intervertebral disc. The discectomy may create a space for a spinal implant. The amount of removed disc material may correspond to the size and type of spinal implant to be inserted.
Spinal surgery may be complex due in part to the proximity of the spinal cord and/or the cauda equina. Preparation instruments and spinal implants may need to be carefully inserted to avoid damage to nerve tissue. Alignment and spacing of a spinal implant that is to be inserted into a patient may be determined before surgery. Achieving the predetermined alignment and spacing during surgery may be important to achieve optimal fusion of adjacent vertebrae.
Bone graft and/or bone implants may be used to promote bone growth that will fuse vertebrae together. Bone graft may be autogenic bone, allogenic bone, synthetic material, xenogenic bone or combinations thereof. Autogenic bone is bone obtained from another location of a patient. Allogenic bone is bone derived from the same species as the patient. Xenogenic bone is bone derived from a species other than that of the patient. Implants may be formed of metal, polymers, ceramics, inorganic compositions, autogenic bone, allogenic bone, xenogenic bone, or combinations thereof.
Spinal implants are described in U.S. Pat. No. 5,653,763 to Errico et al.; U.S. Pat. No. 5,713,899 to Marney et al.; U.S. Pat. No. 6,143,033 to Paul et al.; U.S. Pat. No. 6,245,108 to Biscup; and U.S. Pat. No. 5,609,635 to Michelson, all of which are incorporated by reference herein as if fully set forth herein.